Process of treating metal



July 2s, 1925.

W. G. HOUSKEEPER PROCESS 0F TREATING METAL Filed Aug. 50. 1920 W. ./y. rw! an me nk ww mno. 6. m M V/ M ,a

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Be' iaimown that I, "n c. Housxnm'nix, a citizenA of ,the United States, -residin zat New York, in the count of New ork and vState -of New York, ave invented certain new and useful Improvements in of Treating Metal, of which the following is a full, clear, concise, and exact description. y y

This invention relates to -a process of treating metal and has particular reference toa. process in which metal is treated to high heat in a vacuum.

' The object of the invention is to provide a siin le, efficient, and economical rocess where y in'th reparation of metal ic and other parts of dxdvices such, for example as the metallic and other parts of thermionic discharge devices, the metal and other dportions are thoroughly cleaned and .ri o vapours and gases contained there-1n and are handled to a minimumdegree after treatment and before assembly in their ultimate positions in the devices with which they are used. While Lhave cited thermionic discharge devices,.it is to be clearly understood that the invention is useful in .other situations in which the same requirements are to be fulfilled, such as the preparation of metal for chemical analysis, the

reparation of metal to be used in `any aboratory experiments where freedom from dirt and gas and wvapour is desirable.

The invention in general comprises the` x the order of 1100 degrees C. for several hours while the interior of Vtheoven is evacuated to a high degree.

This process is related to the processl set forth in Patent No. 1,456,523, May 29, 1923,

method of treating metals in the name of` Russel F. Trimble.

The invention is'illustrated in the drawof which Fig. 1 represents a longitudiin nisection, with some parts in elevation, vofan electric oven which is used'to carry yheater tube 5 of refractor out a step in the precess; Fig. I2 represents a thermionicfdischar e device the metallic` parts of which can treated in accordance with the process.

As shown in the drawing,.5w-ith reference to Fig. 1, the electric oven which is preferably, although not necessarily, used in the carrying out of the process comprises an outer container 1, and an inner receptacle 2, which are spaced apart. The outer container is provided with inlet and outlet ports 3 and'4 respectively for the circulation of a cooling medium around the inner -receptacle. Within .the inner rece tacleis a material around which is wound an electrical heater wire 6. This wire is connected to contact lates. 7 and 8 with which terminals 9 an -10 are f adapted to make contact. These terminals are carried by an insulatingv late 11 referably of heat resisting glass w ich is a apted to rest on a lflange 12 of a metallic cap 13 for the upper end of the inner receptacle 2. `Circuit wires 14 and 15 connect the terminals 9and 10 with 'any' suitable source of power. Within the receptacles 2 and around theheater tube 5 is positioned a pluralit offhighlpolished reflecting surfaces 16, 1 and 1,8. ese surfaces are preferably formed of cylindrical nickel sheets polished on both sides. The charge for the oven is placed within the heater tube 5 and rests upon a support 19 comprised of a lurality of highly polished nickel plates. "Albove'the char e is lacedl another similar set of high y poli ed plates 20. For a more -detailed description of the structure of the oven referencemay be had to a co-pendin pplication filed' August 24, 1920,' Seria umber 405,768, electrical heating ovens in the naine of M. J. Kelly and T. R.'

Griith. The vacuum within the receptacle 2i`s produced by connecting the pipe 2l with a vacuum pump). In Fig. 2 1s s device, the treatment of the metal and other .parts of which forms an example of the operation o f-my4 process. This device comprises an vevacuated vessel 3()v having a stem 31 of glass. Above the stem 3 1 is located a framework comprising a pair of blocks 32 and 33 of insulating material such as lavite, a commercial form of steatite, which are to be treated and `which are con own'a thermionic dischargeico nected and spaced by means of a pair of rods 34 and 35 of nickel. An anode or plate electrode 36 is welded along its edges to the rods 34 and 35. A spiral grid or control electrode 37 is supported within theanode 36 from wires such as 38. A cathode or l filament 39 is supported within the grid 37 ,pliier by causing positive ionization. It`

and the anode 36 by wires such as 40. For a detail description of this thermionic discharge device reference may be had to a col pending applic-ation filed July 20, 1920,

Serial Number 397,764, in the nameof William G. Houskeeper. The frame above described, together with the electrodes, is sup-y ported from the stem 31 by means of angle bars 41 and 42 which are welded at their upper ends to the anode 36 and at their lower ends are fastened, viz, welded, to a collar 43 which surrounds the stem 31.

In carrying out the process of this invention, if theV framework and the electrodes with the supporting bars and collar are composed of highly refractory material, they may be completely assembled ready for mounting on the stem 31. For instance, the

collar 43, the bars 41 and 42, and the anode 36 may be all welded together as a unit. To

this unit may be added the rods 34 and 35,-

the blocks 32 and 33 and the grid 37 with its supporting wires 3S. It is desirable that the electrode unit, including the frame-work, be treated to a high temperature in a vacuum to rid it of vapors, gas, and volatizable impurities which may reside therein, `so that when later` lassembled in the vessel 30 and in actual operation, these parts will not emit vapor and gas which would interfere with the proper operation of the tube as. an amhas been found that if the material in sheet form, or other form in which it is to be had on the market, is treated to eliminate the impurities above referred to, thesubsequent processes of stamping, forming and welding the material to form the completed article, and the great amount of handling necessary in these processes, causey the electrodes and other parts to acquire volatizable impurities, such as oil or grease. This is avoided by treating the unit at a suitable temperature in a sultable vacuum oven such as the one above described. With highly re fractory materials,- a temperature of 1100 or 1200 degrees centigrade may be obtained and maintained for one-half to three hours at a pressure of the order of 10'3 mm. of

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Where some of the elements are of less refractory materials, a somewhat different process covered by the above mentioned Trimble application .is employed. For eX- ample, the grids and vplates are frequentlyY made of nickel and are not capable of withstanding the high temperatures to which the lavite blocks may be subjected. If the filaments are made of oxide coated platinum, it is not desirable to treat them in the oven at all, since the small'amount of impurities contained in the filament may be removed during the pumping of the vacuum tube. In this case, the-manufacture of each electrode and associated' parts is carried as far as possible before the complete assembly of the unit. TheV lavite blocks, after hav-` ing been shaped and drilled, are treated in the oven separately at a temperature of 1100 to 1200 degrees centigrade. The grids and plates are reduced to their final form ready for assembly and are treated at a temperature of about 950 degrees centigrade. The complete unit is then assembled as above described, an`d can be placed in the tube withvout having acquired any considerable amount of impurities.

While three hours have been stated to be a suitable period for treating a considerable quantity of material, this period will, of course, vary with the kind and amount of material to be treated. A

It is understood further that the details of the various steps may be varied without Vdeparting from the spirit of the invention my name this 23rd day of August A. D.,

WILLIAM G. HOUSKEEPER. 

